Tuesday, February 13, 2024 Winter Storm

 A significant winter storm is expected to impact southern New England overnight Monday through Tuesday afternoon. Southern areas, especially towards the coast will see rain to start, however, any rain is expected to transition to snow. Portions of the region will see a heavy, wet snow with strong winds along the coastal Plain. This will introduce the likelihood for scattered power outages. 

Synopsis

A potent piece of shortwave energy within the southern stream becomes an open wave as it rapidly ejects northeast from the southern Plains through the Tennessee Valley and towards the northeast. Meanwhile, shortwave energy within the northern stream undergoes slight amplification as it digs southeast across Canada. Several days ago, there were signs these two energies would phase. This would have resulted in an even more powerful storm, but could have raised concerns about track and how far north the rain/snow line would reside. The more likely scenario now is the northern stream acts as a bit of a kicker, this should help the system track a bit farther south and east, increasing the likelihood that most everyone sees accumulating snow:

Surface low pressure associated with the southern stream vorticity initially is located well inland, closely matched with the placement/track of the vorticity as the system is initially closed. However, as the wave opens up, the surface pressure will weaken with a secondary area of low pressure developing around Delaware/Maryland then tracking east-northeast, passing south of Long Island. The low-level and 700mb low pressure development track will be a bit northwest of the surface low. This will favor heavy precipitation traversing much of southern New England:

The 12z GFS suggests intense lift traversing across southern New England evident by strong frontogenesis moving across the region. This is very consistent with several other forecast models as well:

Discussion

The most noteworthy aspect of this storm will be the forward speed. This will be a factor in preventing greater accumulations from occurring. The worst of the storm will likely be confined to a 3-4 hour window where snowfall rates will range 1.5'' - 2.5'' per hour. Another factor influencing accumulations will be snowfall ratios. The greatest ratios will be across the far interior where a colder thermal profile will support greater snow growth and fluffier snow. Snowfall ratios across the far interior should range anywhere between 10:1 and as high as 13:1. Moving south across the region (through central and southern Connecticut into southeastern Massachusetts) snowfall ratios may struggle to near 10:1 and could be less. 

With a deepening surface low pressure, winds will increase towards the coastal Plains where winds could gusts 30-40 mph. This may induce blizzard conditions at times and lead to very low visibility. Inland winds may gust 20-30 mph yielding low visibility and some blowing/drifting snow where the snow is drier in nature. 

Power outages could become a concern towards southern areas where wind gusts will be stronger and snow will be more on the wet and heavier side. 

With this, let's get into the forecast:

• Precipitation begins across southwestern Connecticut during the mid-to-late overnight Monday with precipitation overspreading areas to the north and east during the early morning. Many areas (especially along and south/east of I-84) may even briefly begins as rain or a wintry mix, however, precipitation should quickly change to snow. 
• Snow intensity picks up extremely quickly, with the heaviest of the snow falling between about 9:00 AM through about 3:00 PM before rapidly tapering off. Snow tapers off quickly from the southwest to the northeast with the more intense snows occurring later and ending later farther northeast in the region. 
• Snowfall rates during the height of the storm range between 1.5'' per hour and 2.5'' per hour. 
• Winds along the coast gust 30-40 mph. Scattered outages are possible due to strong wind gusts combined with heavy, wet snow. 
• Winds farther inland gusts 20-30 mph. Power outages will be more on the isolated side and occur where snow is on the wetter side. 
• Major travel impacts are likely Tuesday. Travel is not recommended unless it is high priority.

Below is what I am thinking: